1. Field of the Invention
The invention relates to an oil pump for an internal combustion engine. The oil pump is provided for the purpose of drawing up the lubricating oil from an oil collector device. The pump has an oil pump housing wherein at least two pairs of gears are disposed. The pairs of gears, in order to form the pumping stages, are connected on the suction side to a suction passage formed in the oil pump housing and on the delivery side to a delivery passage.
Commonly assigned German published patent application DE 101 59 088 describes a gear oil pump for the supply of lubricating oil to an internal combustion engine, wherein the lubricating oil is delivered from a rear oil suction space of an oil collector housing of the internal combustion engine via a first pumping stage into the actual oil sump in order to be supplied from there via a second pumping stage to the consumers, such as, for example, the main bearings of the crankshaft or the bearings of the camshaft, etc. Particularly during relatively long downhill sections, the first pumping stage may suck up air, with the result that the relevant pair of gears of the pumping stage is not, under some circumstances, sufficiently lubricated. Sufficient lubrication of the gears is required in particular if pumping stages connected downstream are driven via the relevant pumping stage and therefore a corresponding torque has to be transmitted.